Atrial fibrillation (AF) is a disturbance in the rhythmic beating (or arrhythmia) of the upper chambers of the heart. AF is the most common sustained cardiac arrhythmia, responsible for almost 50% of hospitalizations for arrhythmias (Benjamin E J, et al. 1998; Wyse D G, et al. 2002; Benjamin E J, et al. 1997; Allessie M A, et al. 2001). Consequently, AF is a significant cause of morbidity and mortality. Treatment of AF has been hampered by ineffectiveness of drugs. Moreover, attempts to terminate AF with electrical shocks, using a process termed “cardioversion” works for only about one-half of the patients during the first 6-12 months. Consequently, a “simple” means to identify patients in whom cardioversion would effectively terminate AF would be beneficial in terms of saved time and money.